steels



(No Model.)

E. J. STEELE.

DUPLEX TUBE.

No. 435,193. Patented Aug.26,1890.

Flt 476a JSte [e UNITED STATES PATENT OFFICE.

ELISHA J. STEELE, OF TORRINGTON, CONNECTICUT, ASSIGNOR TO THE COE BRASSMANUFACTURING COMPANY, OF SAME PLACE.

DUPLEX TUBE.

SPECIFICATION forming part of Letters Patent N 0. 435,193, dated August26,1890.

Application filed July 5, 1890. Serial No. 357,810. (No model.)

To aZZ whom it may concern.-

Be it known that I, ELISHA J. STEELE, a citizen of the United States,residing at Tori-ington, in the county of Litchfield and State ofConnecticut, have invented certain new and useful Improvements in DuplexTubes; and

I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to to whichitappertains to make and use the same.

This invention relates to certain novel and useful improvements induplex tubes and the method of producing the same, and has forits objectto produce a tubing of round or oval t 5 section, whose interior shallbe unequally divided into two passages or conduits, and likewise it isan object of my invention to provide an exceedingly simple method ofassembling and uniting the parts of which the tube is made; and withthese ends in View my i11- vention consists in the method and in theconstruction which will be presently set forth, and then designated inthe claims which are hereunto annexed.

In order that those skilled in the art to which my invention appertainsmay fully understand its construction and the method whereby it isproduced, I will describe both of these in detail, reference being hadto the 0 accompanying drawings, which form a part of this specification,in which- Figure 1 is a transverse section through the oval tube, whichis shown in perspective at Fig.2. Fig. 3 is a perspective of the comple-3 5 mentaryportion of the finished tube, and Fig.

4 a transverse section thereof. Fig. 5 is aplan view showing the twoparts in position to be united; Fig. 6, a transverse section of the twoparts .in position to be joined, but not join ed;

Fig '7, a plan view of the parts shown at Figs.

3 and 4:; Fig. 8, a perspective of the finished tube, and Fig. 9 asection showing a modification. Like numerals and letters of referencede- 5 note the same parts in all the figures.

The purpose for which this duplex tubing is commonly used is to conveygas and at the same timefurnish a protectiug cover for electric wires asused in so-called combination- 5o fixtures. It is therefore essentialthat the gas-duct should be tight, but it is not strictly brazing thejoint to in the oval tube.

necessary that the way for holding the wires should be likewise. In factthe reverse may be convenient.

In the manufacture of my improved tubing I first take a strip of sheetmetal and by means of suitable dies bend the same into the oval formshown at Figs. 1 and 2, thereby forming a tube 1, whose edges meet in abuttjoint. I then bend another strip of metal into the general U shapeshown at Figs. 3,4, and 7 and designated by the numeral 2. In bendingthe part 2 its curve should be substantially identical in radius withthe major curves of the tube 1,so that when assembled, as hereinafterset forth,the completed article will be cylindric. Having thus made thetwo pieces, I place them in assembled position,as seen at Figs. 5 and G,and then braze the abutting edges b, at the same time preferably Thecompleted tube may then, if required, be passed through suitable dies,so as to conform its exterior to the exact shape required and also tosmooth the joints which have been united by the brazing process.

The oval shape of the tube 1, l deem to be important for severalreasons. In the first place, since this is the duct through which theelectric wires will be drawn, it is impor- 8o tant that its interiorshould be smooth and without acute corners, such as those seen in thelarger duct, which latter is designed to carry the gas and whose shapeis therefore immaterial. It will also be observed that the edges of thetube 2 meet the minor curves of the oval tube 1 in perfectly-squareabutting joints, thereby imparting to said tube a certain support, whichadds strength to the structure as a whole.

Another seemingly slight feature of this construction, but one which isof considerable importance, is that the inner side of the tube 1 whichforms the partition in the complete tube does not extend straight acrosssaid tube 5 from side to side and does not divide the tube into twoequal ducts. By reason of this construction I the tube may be bent toform the various curves incident to the manufacture of gas-fixtures withmuch less risk of rupture I00 of the brazed joints than if the tube weredivided into two semi-cylindric passages by a straight partition, whichmanifestly would offer great resistance if attempted to be bentin thedirection of its width. The joint aneed not be brazed at all, and inthat case said joint may be left slightly open for the laying in ofwires, if required, instead of threading them through the tubelongitudinally, after which the joint may be closed, or it may be leftopen to afford access to the Wires for purposes of repair. Thisconstruction I have shown at c, Fig. 9.

I am aware that duplex tubes are not broadly new, and that a tubecomposed of two semi-cylindric duets with a straight dividing-partitionhas heretofore been made.

I do not, therefore, desire to be understood as laying claim to eitherof these as my invention.

What I claim is- 1. A duplex tube consisting of an oval tube 7 havingits joint extending longitudinally of one of its major curves, incombination with a U-shaped complementary portion whose edges abutagainst the minor curves of the oval tube, whereby the completed articleis divided by a curved partition into two ducts of unequal size,substantially as described.

2. A duplex tube, the same consisting of the oval tube 1, having thejoint (1, and the U-shaped part 2, whose curve is of the same radius aseach of the major curves of the tube 1 and meet the ends of one of saidcurves to form the joints b,whereby a cylindric but unequally-dividedtube is produced, substantially as described.

3. The dupleX tube adapted to carry gas and electric Wires, the sameprovided with the tight duct 2 and the parallel duct 1, the interior ofthe latter being accessible through the open joint a, substantially asdescribed.

4. The method of making duplex tubing, which consists in first drawing astrip of sheet metal into a tube of oval section, then drawing aU-shaped tube Whose curve is the same as each of the major curves of theoval tube and whose edges are adapted to abut from Without against theminor curves of said oval tube, and then brazing or otherwise securingthe joints.

In testimony whereof I aflix my signature in presence of two witnesses.

ELISHA J. STEELE. Witnesses:

CHAS. F. BROOKE, E. T. Con.

